With the rapid progress of a portable electronic device such as cellular phone and notebook computer, demands for increasing the capacity of a battery used in its main power supply or backup power supply are increasing, and a nonaqueous electrolyte battery such as lithium ion secondary battery having a high energy density as compared with a nickel•cadmium battery or a nickel•hydrogen battery is attracting attention.
A representative example of the electrolyte solution for a lithium ion secondary battery is a nonaqueous electrolyte solution prepared by dissolving an electrolyte such as LiPF6, LiBF4, LiN(CF3SO2)2 and LiCF3(CF2)3SO3 in a mixed solvent consisting of a high-permittivity solvent such as ethylene carbonate and propylene carbonate and a low-viscosity solvent such as dimethyl carbonate, diethyl carbonate and ethyl methyl carbonate.
As for the negative electrode active material of a lithium ion secondary battery, a carbonaceous material capable of occluding•releasing a lithium ion is mainly used, and representative examples thereof include natural graphite, artificial graphite, and amorphous carbon. With an attempt to more increase the capacity, a metal- or alloy-based negative electrode using silicone, tin or the like is also known. As for the positive electrode active material, a transition metal composite oxide capable of occluding•releasing a lithium ion is mainly used, and representative examples of the transition metal include cobalt, nickel, manganese, and iron.
Such a lithium ion secondary battery uses positive and negative electrodes having high activity and therefore, it is known that the charge/discharge capacity is reduced by a side reaction of the electrode with the electrolyte solution. In order to improve battery characteristics, various studies are being made on the nonaqueous solvent or electrolyte.
Patent Document 1 has proposed using a vinylene carbonate or its derivative, where a cyclic carbonate having a double bond preferentially reacts with the negative electrode to form a high-quality film on the negative electrode surface and the storage characteristics and cycle characteristics of the battery are thereby enhanced.
Patent Document 2 has proposed using a nonaqueous electrolyte solution containing an alkyl alkanesulfonate compound, where a film having high lithium ion permeability is formed by a reaction on the carbon electrode surface and the charge/discharge cycle life is thereby enhanced.
Patent Documents 3 and 4 have proposed using a nonaqueous electrolyte solution containing an alkynyl alkanesulfonate compound or a dialkylsulfonic acid ester, where a passivation film is formed on the carbon negative electrode surface and the charge/discharge cycle life is thereby enhanced.